Background: S100A10, of the S100 protein family, is reported to be involved in cancer cell invasion and metastasis. The aims of the present study were to immunohistochemically examine S100A10 expression in surgically resected lung adenocarcinomas, and evaluate any relationships with clinicopathological parameters and prognosis of patients. Materials and Methods: S100A10 expression was immunohistochemically studied in 202 consecutive resected lung adenocarcinomas, and its associations with clinicopathological parameters were evaluated. Kaplan-Meier survival analysis and Cox proportional hazards models were used to estimate the effect of S100A10 expression on survival. Results: S100A10 expression was detected in 65 of the 202 (32.2%) lung adenocarcinomas, being significantly correlated with poorer differentiation (P =0.015), a higher pathological TNM stage (stages II and III) (P=0.004), more frequent and severe intratumoral vascular invasion (P=0.001), and a poorer prognosis (P=0.030). However, S100A10 expression was not an independent predictor of survival after controlling for clinicopathological factors. Conclusions: The present study reveals that S100A10 is expressed in a subset of lung adenocarcinomas, and this is related to some clinicopathological parameters, although further studies are required to confirm the correlation between S100A10 expression and prognosis of lung adenocarcinoma patients.